Burglar alarm



June 421, 1927.

,Y l ,633,468 J. yYENDRUGH BURGLAR 'ALARM Filed Deo. 30. 1922 FIG. 1.

@M Wttouwq Patented June 21, 1927.

UNITED sTATEsPAT-ENT OFFICE.

JOHN YEN'DRUCH, or wamnnnoaonrnnro, CANADA.

BURGLAR ALARM.

Application filed December 30, 1922. Serial No. 610,065.

This invention relates Ito kcertain new and useful improvements in burglar alarms, and has particular reference to an alarm device associated with 'the lock mechanism of a door adapted for operation for sounding an alarm when the knob spindle of the door lock is rotated.

lVitli the above and other objects in view f as the nature ot the `invention is better un derstood, the saine consists of the novel form,

' combination and arrangement of parts here-v inattesi1 more fully described, shown in the accompanying drawing'and claimed.

`In the drawing,-wherein like reference characters designate corresponding parts throughout the several views,

Figure 1 is a front elevational view of a A door and trame equipped with the improved burglar alarm mechanism, an electric bell, battery, wiring and switch being shown as associated therewith,

Figure 2 is a top plan view of the lock casing removed from the door with the cover ot' the casingy removed showing the electric wiring associated with ther lock mechanism,

Figure 3 is a detail sectional yview showingv an insulated mounting ft'or a contact arm clamped between `adjacent edge walls of the lock casing, Y n y I kFigure 4 is' a `fragmentary Vdetail view showing the Contact arm in side elevation,

Figure 5 is a side elevational view of a conventional form of rotatable hand switch, Figure 6 is a top plan view of the switch, Figure 7 is a top plan view of the switch with a portion of the cover removed, and

Figure S is a top plan view with the switch cover removed showing the side contacts and the cross switch arm.

Referring more in detail to the accompanying drawing, and particularly to Fig. 1,

there is illustrated a burglar' alarm associatv ed with a. door 1 liingedly mounted in a frame 2, the door carrying the usual lock mechanism casing 3 that encloses a key shiftable locking bolt 4 having a guard plate 5 associated therewith and tensioiied by the spring 6 that is mounted upon the pin 7. The latch 8 is connected to the tensioned plate 9 carrying rearwardly directed spaced arms 10 between which the knob spindle 11 projects, the knob spindleshifting the lateral arms 12 that engage the bent ends 13 of the arms 10 for retracting the latch 8.

.and preferably anchored upon the 4plate 27 carrying characters The. alarm mechanism associated with the door lock includes a battery 14 having a lead Wire 15 that ext-ends to a bell 16, a` wire 1 extending from the bell to the lock casing 3, l spring supporting pin 7 as shown in Fig. 2, the wire 17 being thereby grounded to the lock mechanism, The lead wire 18 extending from the other pole of the battery 14 kpasses through and is electrically connected to the rotatable hand switch 19, the wire 20 leading from the switch 19 being connected to the pin 21 encased in the cylindrical insulator 22 having side grooves 23, more clearly shown in Figs. 2 and 8 to receive the adjacent edges of the klock casing walls `for anchoring the pin 21 in position. The inner end ot the pin carries a contact arm 24 having an in sulating path of moven'ient of one ot thev bent ends 13 of the arm 10. i f

The rotary switchis ci the usual type einbodying a turn button 26 Afor shifting the 28 viewable through the opening 29 to indicate the on and olf positions of the switch, the knob 26 further operating they cross switch arms 30 for moving the same into engagement with the side contacts 31.

From the above detail description of the device, itis believed that the construction and operation thereof will at once be apparent, it being noted that when the switch 19 is rotated to ay closed position, rotation ot the knob spindle 11 for retracting the latch 8 will cause the bent end 13 of one oi the arms 10 to engage the iree end of the contact arm 24 tor closing the circuit and through the system of wiring and battery 14, sound the bell 16, the projection of the latch 8 separating the arm 10 and contact 24, as will at once be obvious from an inspection of Fig. 2. The contact arm 24 is rigidly supported in the lock casing through the medium of the pin 21 and the insulating bushing 22, such mounting maintaining the contact arm in its proper position to be engaged by the arm 1() of the sliding plate that operates the latch.

While there is herein shown and described the preferred embodiinentof the present invention, it is nevertheless to be understood that minor changes may be made therein without departing from the spirit and scope of the invention as claimed.

that is claimed as new is 1- l. In a. burglar alarm electric circuit closer, the combination with the encased lock mechanism ot' a door having an electric wire grounded thereto, of a pin inclosed in an insulating sleeve clamped between adjacent edges of the lock casingparts at the rear end thereof, a. second electric wire connected to the outer end of said pin, a flexible contactl arm having one end thereoll xed to the inner end ot said pin normally lying parallel with the end wall ot the casing and spaced there'irom, and having its free end disposed in tl'ie path ot increment ot' a movable part oit the lock mechanism, and a bull'er insulator ixed to the contact arm intermediate the ends thcreol and so positioned with respect to the tree Contact end olf the arm to prevent accidental engagement between the contact arm and (.:asing and per mitting the flexing of the contact arm when engaged by a part ot the lock mechanism to move into contact with the lock casing.

Q. In an alarm latch, the combination o't a door latch, wherein a. casing carries a hori- Zontally sliding latch bolt having a bifurcated inner end, and wherein a knob spindle ca `ries lateral arms associated with the bifurcations of the latch bolt for effecting retraction oit the latter upon turningof the knob spindle, a horizontal binding post ele ment insulated from and extending through the inner end of the latch casing substantially in opposed relation to the lower furcation oit the latch bolt, and normally open circuit closing means including a. flexible resilient contact arm lixed at its lower end on the inner end or the binding post eleof the latter.

In an alarm latch, the combination of a door latch, wherein a` casing carries a hori- Zontally sliding latch bolt. having a bifurcated inner end, and wherein a knob spindle carries lateral arms associated with the bifurcations ot the latch bolt tor etlecting 4retraction ot the latter upon turning of the knob spindle, a horizontal binding post element insulated Ytroni and extending through the inner end ol the latch casing substantially in opposed relation to the lower turcation of the latch bolt, and normally open circuit. closing means including a flexible resilient contact arm fixed at its lower end on the inner end ol" the binding post element and having Vtree upper end disposed in the path oi movement of the upper liurcation ot the latch bolt, said. contact arm being normally disposed adjacent to and substantially Iparallel with the inner end oit the latch cas ing so as to have its ntree upper end forced inwardly7 into engagement with the inner end ot the latch casing` by the upper urca tion ot the latch bolt upon retraction of the latter, and an insulator butler on the inter'- medate portion ot the contact arm 'for pre- Venting engagement oiI the latter with the .casing except when the ytree upper end of the contact arm is flexed inwardly.

In testimony whereof I alli); my signature.

JOHN YENDRUCH. 

